The invention relates generally to the treatment of protein-polysaccharide complexes. Of special interest to the invention is a method of producing products of high protein content from wheat flour and, even more particularly, from wheat gluten.
Wheat possesses a higher percentage of protein than any other type of grain. Thus, wheat as such contains about 12.0 percent by weight of crude protein. On the other hand, wheat flour contains about 14 percent by weight of protein substances on the average. These protein substances consist predominantly of gluten. The latter is an elastic, rubber-like protein substance which forms an inherent part of the wheat. The characteristic consistency of the gluten after mixing with water determines the baking properties of the wheat flour.
The gluten is obtained from the wheat flour by washing out the latter with water. During this operation, the starch present in the wheat flour is removed in the form of a starch emulsion and the gluten remains behind as an elastic mass. The starch present in the wheat and recovered by washing out of the wheat flour is frequently accorded no more significance than merely a side product obtained during recovery of the gluten.
The gluten contains both water-soluble and water-insoluble proteins, that is, the protein content of the gluten is partially water-soluble. Of the proteins present in the gluten, the water-soluble proteins represent a desired product in the food and pharmaceutical industries. Thus, the water-soluble proteins are particularly easy to digest and may be incorporated into foods in spray-dried or freeze-dried form. Advantageously, the water-soluble proteins are used in baby foods, for dietetic purposes and for geriatric purposes.
Certain problems arise in the prior art. On the one hand, the gluten produced according to the known procedures contains a maximum of 60 percent by weight of crude protein. It is not possible to achieve a higher protein concentration by washing out the wheat flour with water in accordance with the conventional methods. On the other hand, it is not possible to readily recover the water-soluble proteins present in the gluten in the form of a product having a high concentration of protein.